PCP Regulator Failure

[Robert_Lavin]

Slightly techy question for a Friday afternoon.

What's the mechanism of failure that causes a regulator to stop regulating?

Given that it's just some springs, seals and a diaphragm(?) I'm struggling to work out what goes wrong.

Anyone have any expertise they can share?

Thank you.

[AdeC]

Usually the seals

[Neil54]

Turning a regulator down whilst under pressure damages the springs.
The seat can become worn.

O rings of course.

[angrybear]

Unnecessary lube gumming up with dirt & debris, or the springs failing having been driven too hard,
but as said above O rings are most likely

[rapidresponse1]

id say the 0 rings

[deejayuu]

Synthetic valve seat as Huma, Uragan, etc deforms under pressure from metal valve nipple. Got photos if it helps.

[Robert_Lavin]

Synthetic valve seat as Huma, Uragan, etc deforms under pressure from metal valve nipple. Got photos if it helps.

Hadn't thought about that.

I trying to understand why a failed regulator gives the low-high-low power change from a full fill like an unregulated gun.

I suppose I need to understand why the unregulated power curve is as it is.

[Anothermiss]

Hadn't thought about that.

I trying to understand why a failed regulator gives the low-high-low power change from a full fill like an unregulated gun.

I suppose I need to understand why the unregulated power curve is as it is.

Because the reg has failed, it's no longer in the equation, so the gun will run as unregged in its characteristics. The curve comes from the influence of the springs (hammer, valve return) which are a fairly repeatable pressure. The bottle is in a constant pressure decline shot by shot. The bottle pressure pushes back against the valve as a return pressure. The hammer and spring assembly works against this to knock the valve open. Because the pressure from the bottle is slowly declining, the hammer knock open has slight more eefect on knocking open the valve as the resistant pressure in the bottle drops (more dwell time in the open position) so power rises. However, once the peak of the bottle pressure/dwell/power is achieved, the pressure in the bottle will continue to fall and the dwell time is of no consequence as the bottle pressure cannot realistically achieve the power it did at higher pressure. That is the downward arc of the curve.

A reg, if it's working correctly, will draw from the reservoir (bottle) and create a second chamber of regulated air at a fixed pressure. You then have a fixed spring pressure setup working against a constant pressure.. ... This is the consistency a reg achieves. Until the bottle pressure drops below the reg setting and then you're "off reg" and the inconsistency returns.
If your reg is set correct, there should be no "spike" in power as you come off reg.

[Robert_Lavin]

That's just the explanation I needed. Thank you. I wasn't considering the interactions of the springs with the pressure in the reservoir.

So even if seals are fine, a damaged valve seat will still not seal properly leading to a non-regulating regulator.

I was struggling to get my head around the initial low power section of there curve.

Thanks all.

[Anothermiss]

That's just the explanation I needed. Thank you. I wasn't considering the interactions of the springs with the pressure in the reservoir.

So even if seals are fine, a damaged valve seat will still not seal properly leading to a non-regulating regulator.

I was struggling to get my head around the initial low power section of there curve.

Thanks all.

Yes, the reg will "creep" up to reservoir pressure.